1. Field of the Invention
This invention generally relates to magnetic alloy compositions and permanent magnets and, more particularly, to magnetic alloy compositions and permanent magnets comprised of rare earth elements, actinide elements and metals.
2. Description of the Prior Art
Permanent magnets are used in a wide range of electrical equipment, such as various electrical appliances and computer devices. Advances in electronics have caused integration and miniaturization of electrical components, thereby resulting in an increasing demand for new and improved permanent magnet materials.
Known permanent magnets include alnico, hard ferrite and rare earth/cobalt magnets. Recently, permanent magnets have been introduced containing iron, various rare earth elements and boron. Known methods for producing such magnets include preparation from melt quenched ribbons and by the powder metallurgy technique of compacting and sintering. For example, U.S. Pat. No. 4,802,931, Croat, discloses an alloy with hard magnetic properties having the basic formula RE.sub.1-x (TM.sub.1-y B.sub.y).sub.x wherein RE represents one or more rare earth elements including scandium and yttrium in Group IIIA of the periodic table and the elements from atomic number 57 through 71, and TM represents a transition metal taken from the group consisting of iron or iron mixed with cobalt, or iron and small amounts of other metals such as nickel, chromium or manganese. This patent further teaches the production of these permanent magnet alloys from melt quenched material by the process generally referred to in the art as "melt spinning", which is described in U.S. Pat. No. 4,496,395. In melt spinning, the quench rate of the material can be varied by changing the linear speed of the quench surface. By selection of suitable speed ranges, products can be obtained that exhibit high intrinsic coercivity and remanence as quenched.
An example of the powder metallurgy technique is U.S. Pat. No. 4,597,938, Matsuura et al., which discloses the process for producing permanent magnet materials of the Fe-B-R type by: preparing a metallic powder having a mean particle size of 0.3-80 microns and a composition consisting essentially of, in atomic percent, 8-30% R representing at least one of the rare earth elements inclusive of Y, 2 to 28% B and the balance Fe; compacting; and sintering the resultant body at a temperature of 900.degree.-1200.degree. C. in a reducing or non-oxidizing atmosphere. Co up to 50 atomic percent may be present. Additional elements M (Ti, Ni, Bi, V, Nb, Ta, Cr, Mo, W, Mn, Al, Sb, Ge, Sn, Zr, Hf) may by present. The process is applicable for anisotropic and isotropic magnetic materials. Additionally, U.S. Pat. No. 4,684,406, Matsuura et al., claims a certain sintered permanent magnet material of the Fe-B-R type, which is prepared by the aforesaid process. Also, U.S. Pat. No. 4,601,875, Yamamoto et al., teaches permanent magnet materials of the Fe-B-R type produced with the additional step of subjecting the sintered bodies to heat treatment at a temperature lying between the sintering temperature and 350.degree. C. However, none of these prior art references suggest the novel magnetic alloy compositions and permanent magnets of the present invention.